Braking rotating components and cooling means

ABSTRACT

Apparatus having a rotatable component such as a brake disc has braking means capable of applying a braking couple to the rotating component, a heat-collecting shoe for absorbing heat from the component generated by the braking means, and control means operable to urge the shoe towards the rotating component, the control means being operable independently of the braking means.

M8188 States Patent 1191 Odier Oct. 23, 1973 [54] BRAKING ROTATINGCOMPONENTS AND 2,944,618 7/1960 Schjolin 188/264 D COOLING MEANS2,788,870 4/1957 Heck 1 188/264 P 2,986,238 5/1961 Eaton 192/113 B XInventor: J Alfred OdIer, y, France 3,217,844 11/1965 Nelson et a1 192113 A x [73] Assignee: Societe Anonyme Francaise du Ferodo, Paris,France Primary Examiner-George E. A. Halvosa [22] Flled: 1971Att0meyRobert .1. Patch and Irving S. Thompson [21] Appl. No.: 175,199

30 F ei nA licat'on Pr 't D ta 1 or g pp y a 57 ABSTRACT Sept. 4, 1970France 7032180 521 US. Cl. 188/71.6, 188/264 D, 188/264 R, Apparatushaving a rotatable component Such as 192/113 R, 192]] 13 A brake dischas braking means capable of applying a 51 1111.0. Fl6d 65/84 brakingcouple to the rotating component, a heat- [58] Field of Search 188/264R, 264 A, collecting Shoe for absorbing heat from the p 188/264 AA, 264D, 71.6; 192/113 A, 113 B, nent generated by the braking means, andcontrol 3 R means operable to urge the shoe towards the rotatingcomponent, the control means being operable inde- 5 References Citedpendently of the braking means.

UNITED STATES PATENTS Runner 188/264 A 9 Claims, 8 Drawing FiguresBRAKING ROTATING COMPONENTS AND COOLING MEANS BACKGROUND OF THEINVENTION 1. Field of the Invention The present invention relates to anyapparatus with a rotating component which includes braking means capableof applying a braking couple to the said rotating component.

Examples of such apparatus include a disc brake, a drum brake, a brakepulley or an eddy current brake, or any decelerator or like device, andthe invention relates to the application of such a brake, decelerator orsuch device to automobile vehicles, machine tools, trains or to otherapparatuses.

However, for simplicity, the subject of the present invention willhereafter be presented by particularly referring to its application tobrakes.

2. Description of the Prior Art In all types of brakes or the like, andin all cases of the application of these, one of the major problems tobe solved is to ensure that in operation the rotating componentsubjected to the braking means should be correctly cooled.

In effect, even in a case where this rotating component in operationreaches a temperature which is not critical, that is to say atemperature at which undesired phenomena occur, such as those calledvapour lock or fading," which are capable of at least temporarilyaffecting the efficiency, it is still of value to reduce thistemperature so as to reduce wear of this rotating component as well asof the associated means of braking, and hence to increase their workinglife.

Where one is dealing in particular with a brake in which the means ofbraking comprise shoes applied to the rotating component, there is valuein reducing to the maximum extent the temperature reached by these shoesin operation, in order especially to reduce their wear and to achieve amore uniform level of friction of the shoes.

It has already been proposed, for this purpose, to combine the means ofbraking with at least one special shoe called a heat-collecting shoe.

However, in the embodiments hitherto known, the heat-collecting shoe iscarried by the same support as the support of the means of braking andis most frequently overlapped therwith. This results in relativelycomplicated and costly apparatus.

The aim of the present invention is to overcome these disadvantages.

SUMMARY According to the present invention, there is provided apparatushaving a rotating component such as a brake, decelerator or the like,including braking means capable of applying a braking couple to therotating component, a heat-collecting shoe, means for control of saidshoe capable of urging said shoe towards the said rotating component,characterised in that the means of control of the said heat-collectingshoe are independent of the said braking means.

The independence of the braking means from the heat-collecting shoeresults in greater ease of construction and in greater flexibility inoperation as compared to the previously known embodiments. Furthermore,it leads to a more rational arrangement of the elements in question,those involved in heating the rotating component being advantageouslyseparated from those involved in cooling the latter.

According to a first possible embodiment, the means of control of theheat-collecting shoe apply the latter against the rotating componentwhich is to be cooled.

In this case, the heat-collecting shoe according to the inventionvirtually does not participate in the braking, the pressure with whichit is applied to the rotating component being chosen to be sufficientlylow that, taking the characteristics of this shoe into account, thetangential frictional force which results, that is to say the product ofthe coefficient of friction of this shoe and its application pressure,is restricted to a fraction of the tangential braking force developed bythe associated means of braking, this fraction being at most 50 percentand preferably less than 10 percent, especially in a case where thisbrake serves as equipment on a touring vehicle.

In other words, since the couple and the tangential force areproportional, the frictional couple due to the heat-collecting shoeaccording to the invention is preferably only a fraction of the brakingcouple applied to the rotating component in question.

According to a second possible embodiment, the heat-collecting shoeaccording to the invention remains at a distance from the rotatingcomponent to be cooled.

In either case, this heat-collecting shoe absorbs at least a part of theheat which is in this rotating component, and the heat thus absorbed bythis shoe is removed by the latter to the surrounding medium, eitherdirectly or via a cooling fluid which is, for example, provided withinthe said shoe; in this latter case, it is advantageously possible to beless demanding as regards the quality of the material of which the shoeemployed consists.

However, this material is preferably chosen so as to have a lowcoefficient of friction, in any case less than 0.3, a good heatconductivity and a good specific heat by volume.

As regards the means of control of the heatcollecting shoe according tothe invention, they can, for example, be independent.

They are, for example, a spring which pulls this shoe in the directionof the component to be braked, or a permanent magnet embedded in theshoe itself.

According to different variants, the means of control of theheat-collecting shoe according to the invention are regulated and are,for example mechanical, electrical or electro-magnetic means, or fluidicmeans, that is to say hydraulic or pneumatic means, under pressure orunder pressure reduction.

In the latter case, such regulated means of control are preferablycoupled to means of control of the braking means in question and aredependent on a timing device which is capable of regulating, during eachbraking process, the period for which the device acts.

As a result of this arrangement, the heat-collecting shoe according tothe invention is not permanently applied against the associated rotatingcomponentiit only becomes involved at the time of the individual brakingprocesses and can continue to act for any chosen period.

In any case, experiments have shown that a heatcollecting shoe accordingto the invention made it possible significantly to lower the temperaturereached in operation by the rotating component concerned, and

also made it possible significantly to reduce the wear, of the variouscomponents involved.

The use of a heat-collecting shoe according to the invention has thefurther advantage of opening up new avenues of use of materials, suchas, for example, stainless steel, which because of their sensitivity tohigh temperatures have hitherto been unusable for the manufacture ofthis rotating component.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a side view of a brakeaccording to the invention;

FIG. 2 is a partial cross-section of this brake, along line IIII of FIG.1;

FIG. 3 is a cross-section of the heat-collecting shoe with which thisbrake is equipped, along line III-III of FIG. 2;

FIG. 4 is a diagram illustrating the results obtained with such aheat-collecting shoe;

FIG. 5 is a view similar to FIG. 3 and relates to a different embodimentof the heat-collecting shoe;

FIG. 6 is a view similar to FIG. 2 and relates to a differentembodiment;

FIG. 7 is an axial cross-section of the means of control which it ispossible to combine with a heatcollecting shoe according to theinvention, in cooperation with means of timing;

FIG. 8 is a schematic representation relating to a variant of thesemeans of control and these means of timing.

DESCRIPTION OF THE PREFERRED EMBODIMENTS FIGS. 1 and 2 illustrate theapplication of the invention to a disc brake, that is to say to a brakein which the rotating component to be braked is a disc 10.

In a known manner, the means of braking associated with such a disccomprise in the example shown, a supporting stirrup l1 straddling thedisc 10, two brake shoes 12 arranged respectively on the two sides ofthe disc 10, and a control block 13.

Such an arrangement is in itself well known; it has hence only beenschematically represented in the figures and will not be described indetail below.

According to the invention, the brake is equipped with a heat-collectingdevice 15 which, in the example shown, is arranged immediately adjacentthe braking stirrup 11, in the direction of rotation F of the disc 10,and possesses a second supporting stirrup 16 engaging on the disc 10.

The stirrup 16 is, for example, a fixed stirrup of which each of thearms is hollowed out to provide a seat 17 for a heat-collecting shoe 18,to slide.

In the embodiment illustrated by FIGS. 1 to 3, a permanent magnet 19 isembedded in the heat-collecting shoe 18, which ensures that this shoe ispermanently applied against the braking disc 10.

According to a different embodiment (not shown), this permanent magnetis replaced by a spring which rests against the stirrup 16.

Such magnets or such springs form means of control associated with theheat-collecting shoes according to the invention, to ensure that thelatter are applied against the disc 10.

According to the different embodiment represented in FIG. 6, the stirrup16 is mounted so as to float relative to the disc 10, and theheat-collecting shoes 18 are associated with a control block 20 whichacts directly on one of these shoes and indirectly on the other, via thestirrup 16.

For example, one may be dealing with a mechanical, electrical,electro-magnetic or fluidic control block, of the type of those usuallyemployed for controlling braking means.

In any case, whether the stirrup 16 is fixed or floating, the controlblock 20 can be regulated so as only to apply the heat-collecting shoes18 intermittently against the disc 10, as will be explained subsequentlyby the various embodiments.

In FIGS. 2 and 6, the heat-collecting shoes 18 do not possess anyinternal cooling system; this cooling takes place by heat exchange withthe surrounding medium.

As a variant, and as shown schematically in FIG. 5, which illustrates adifferent embodiment of the heatcollecting shoe shown in FIG. 3, such aheat-collecting shoe is hollowed out with at least one recess for acooling fluid; these are formed as internal channels 22 which allow sucha fluid to be circulated therein.

Experiments have shown that such heat-collecting shoes made it possibleefficiently to remove a part of the heat which the disc 10 collectsduring braking, and this heat is removed either directly by contact withthe atmosphere or indirectly through the cooling fluid which maycirculate in these shoes; the experiments have also shown that acirculation of cooling fluid was particularly desirable where theheat-collecting shoes 18 are permanently applied.

The results of these experiments, several of which will be given below,are illustrated by the diagram in FIG. 4.

In this diagram, the temperature T of the disc 10 is plotted as theordinate, as a function of a number N of applications of the brake,plotted as the abscissa.

The curve C1, shown as a solid line, indicates the course of the curverepresenting this temperature T in the absence of the heat-collectingdevice 15 according to the invention, and the curve C2, shown as abroken line, indicates the course of the curve representing this sametemperature if this heat-collecting device is brought into action.

More precise values of this temperature will be given below withreference to the various sets of experiments which have been carriedout.

In all these series of experiments, the braking stirrup l 1 applies abraking couple of deca-newton/m to the disc 10 every secondspThe periodof braking is 7 seconds and this braking is followed by a stoppage timeof 7 seconds.

Under these conditions, the temperature of the disc 10 becomesstabilised at about 430 C after 25 brakings, and the temperature of thelinings of the brake shoes 12 rises and becomes stabilised at C.

The heat-collecting device 15 according to the invention ishydraulically controlled and develops a frictional couple of the orderof 1 deca-newton/m; its shoes 18 have a lining of the type sold underthe trade name of FERODO 437, the coefficient of friction of which isbetween 0.15 and 0.2. I

These shoes are applied intermittently to the disc 10 for 20 seconds ateach braking, the initial moment of application of these shoescoinciding with the start of the braking;

Under these conditions, the temperature of the disc 10 becomesstabilised at about 390 C instead of 430 C previously; the improvementin heat conditions manifests itself from 300 C onwards.

At the same time, the temperature of the linings of the brake shoes 12is lowered to 160 C.

SECOND SERIES OF EXPERIMENTS The heat-collecting device according to theinvention is mechanically controlled and develops a very low frictionalcouple of the order of 0.1 to 0.2 deca-newton/m; its shoes 18 areidentical to those previously tested and are applied for about 20seconds for each braking, the initial moment of application of theseheat-collecting shoes coinciding with the start of braking.

It is found that the heat-collecting device according to the inventionis thus efficient from about 200 C onwards and the temperature of thedisc 10 stabilises itself at about 380 C.

THIRD SERIES OF EXPERIMENTS The heat-collecting shoes employed duringthe second series of experiments are replaced by aluminium shoes cooledby a stream of water and the time of application of thesealuminium shoesagainst the disc 10 is increased to about 30 seconds.

It is found that under these conditions the heatcollecting deviceaccording to the invention is still more efficient than above; afterbrakings, the temperature of the disc stabilises itself at about 220 C.

It is noted at the same time that under these' conditions the wear ofthe linings of the brake shoes 12 is reduced by about percent relativeto the case where the stirrup 1] alone is involved.

FIG. 7 schematically illustrates a possible embodiment of the means ofcontrol which can be associated with the control block 20 of theheat-collecting device according to the invention, in order to regulateits participation, where this control block 20 is a hydraulic block.

In FIG. 7, the general reference 30 denotes a pressure restrictor havingan inlet attachment 31 intended to be connected to the control circuitof the braking stirrup 11 associated with the disc 10, and an outletattachment 32 intended to be connected to the control block 20 of theheat-collecting device according to the invention.

Between the inlet attachment 31 and the outlet attachment 32 thepressure restrictor 30 has a valve 33 designed to co-operate with avalve seat 34.

The valve 33 is coupled to a rod 35 carrying a circlip 36, and betweenthis circlip and a shoulder 37 of the body 38 of the pressure restrictor30 is interposed a spring 39 which pushes the valve 33 open.

The rod 35 which is firmly fixed to the valve 33 forms the plunger coreof an electromagnet 40, in the feed circuit of which are interposedfirstly a contact 40A, parallelled by a self-feed contact 40B, andsecondly a contact 41 controlled by a bellows 42.

This bellows has a fixed face 43, and its free face 44 carries a finger45 which is intended to control the contact 41. g

The bellows 42 are furthermore controlled by a bent lever 46 which ismounted so as to pivot at 47; this lever 46 has firstly an arm 48subjected to the action of a finger 49 carried by the rod 35 which isfirmly fixed to the valve 33, and secondly an arm 50 to which is coupleda return spring 51.

The bellows 42 have a calibrated orifice 56 through which their internalvolume communicates with the atmosphere.

At rest, and as shown, the valve 33 is open, as are the contacts 40A and40B, and the contact 41 is closed; furthermore, the lever 46, of whichthe arm 48 is held by the stop 49 of the rod 35, keeps the bellows 42compressed by means of its arm 50, under the pull of the spring 51.

During a braking action exerted by the shoes 12 of the stirrup 11 underthe control of the block 13 which this stirrup carries, the pressure inthe restrictor 30 rises sufficiently to overcome the axial forcedeveloped by the tared spring 39; the valve 33 closes, thereby isolatingthe control circuit of the heat-collecting device according to theinvention from the braking circuit. Hence the pressure in the controlcircuit of the heatcollecting device from here onwards remains constantat a moderate value determined by the spring 39, for example of theorder of 4 to 5 bars.

At the same time, the closing of the valve 33 has brought about theclosing of the contact 40A and hence of the contact 403, and has causedthe lever 46 to swing in the direction of the arrow 60 of FIG. 7.

As a result of the contact 40B being closed, the electromagnet 40 is inan auto-excited state.

As a result of the swinging of the lever 46 the arm 50 of this leverfrees the bellows 42 which progressively expands through air enteringthrough its calibrated orifice.

This calibrated orifice is so chosen that this expansion lasts about 20to 30 seconds, which extends beyond the duration of the majority ofbraking actions.

Throughout this expansion, the electromagnet 40 re mains under tensionthrough its auto-excitation contact 408 and hence keeps the valve 33closed even if the pressure in the braking circuit has again fallenbelow the value at which the axial force of the tared spring 39 has beenovercome.

.The heat-collecting device according to the invention hence remains inaction.

At the end of the expansion, the finger 45 of the bellows 42 opens thecontact 41, which cuts the feed to the electromagnet 40 and hence freesthe valve 33.

The heat-collecting device according to the invention from here onwardsceases to be in action.

In the case where the duration of braking extends beyond the timing thusprovided by the bellows 42, the valve 33 opens when the braking pressureis relaxed but the heat-collecting device according to the invention hasnevertheless played its role for a sufficiently long period.

FIG. 8 illustrates a hydraulic variant of such means of timing.

In this figure, a pressure restrictor of the type of that describedabove has been shown schematically at this pressure restrictor 70 isconnected by an attachment 71 to the control circuit of the brakingstirrup 11 and through a pipeline 72, equipped with a non-return valve73, to the control circuit of the heat-collecting device according tothe invention.

A capacity of variable volume, 75, is mounted as a shunt on the pipeline72 and comprises a piston 76 which can move in opposition to a spring77, and this piston leaves an annular leakage passage 78. This capacity75 is furthermore connected, at 79, to a leakage return pipeline.

When the braking pressure applied at 71 to the pressure restrictor 70increases, its valve closes, as before which encloses a defined volumeof fluid at a limited pressure in the control circuit of theheat-collecting device according to the invention. The compression ofthe spring 77 maintains a pressure downstream from the non-return valve73, at 72', during which fluid 78 leaks around the piston 76 until thispiston makes contact at 76'.

The period for which this pressure is maintained can be regulated byappropriately selecting the leakage clearance 78.

In all cases, and as in the-embodiment shown in FIG. 7, the pressurerestrictor makes it possible to couple the control of theheat-collecting device according to the invention to the control of theassociated means of brakingv Of course, the present invention is notrestricted to the embodiments described and shown, but encompasses anydifferent execution.

Thus, for example, it is possible to provide several heat-collectingdevices; equally, it is possible to introduce this device or thesedevices at any point on the rotating component which is to be cooled,even on the edge thereof. However, such a heat-collecting device ispreferably placed at the hottest point on the rotating component whichis to be cooled.

Furthermore, in the preceding text, the heatcollecting device ispresented as being fixed; in certain applications, for example inclutches, this heatcollecting device can also be movable.

The preceding text has described a heat-collecting shoe of aluminium. Itwill be apparent that such a shoe can also consist of an aluminium alloyor of a composite material containing aluminium, such as analuminaceramic; of course, the aluminium in these various materials canbe replaced by a different metal and in particular by copper and/r iron.

Preferably, however, the material of which this heatcollecting shoeconsists will be chosen so as to have a low coefficient of friction,less than 0.3, a good heat conductivity, greater than 0.2 cal/cm. sec.C, and a good specific heat by volume, greater than 0.4 cal/ C/cm.

Furthermore, the invention can be implemented by using, as theheat-collecting shoe, any of the shoes of a possible supplementarybrake, such as an emergency brake or, where one is dealing with anautomobile vehicle, an emergency brake or a parking brake.

I claim:

1. An apparatus comprising a rotational component, braking means forapplying braking torque to the rotational component, control means forthe braking means, a heat-collecting shoe for absorbing heat from ,therotational component and having a coefficient of friction less than 0.3,a heat conductivity greater than 0.2 cal./cm.sec. C. and being spacedfrom the braking means peripherally of the rotational component, the

heat-collecting shoe developing a frictional couple with the rotationalcomponent which is at most 50 percent of the tangential braking forcedeveloped by the braking means with the rotational component, meansnormally holding the heat-collecting shoe out of contact with therotational component, and means controlling the shoe for urging ittowards the rotational component, said means controlling the shoe beingoperatively coupled to said control means for the braking means suchthat when said control means for the braking means is actuated to applythe braking means, the heatcollecting shoe is moved into heat-absorbingcontact with the rotational component.

2 An apparatus according to claim 1, wherein said heat-collecting shoehas an internal cooling circuit, and means for circulating a coolingfluid through said cooling circuit.

3. Apparatus according to claim 1, wherein the control means for thebraking means comprises a hydraulic circuit and the means controllingthe shoe is a hydraulic control connected to the said circuit via apressure restrictor.

4. Apparatus according to claim 1 wherein the heatcollecting shoe isarranged adjacent the braking means, in the direction of rotation of therotational component.

5. Apparatus according to claim 1, wherein the rotational component is abrake disc.

6. An apparatus according to claim I, further comprising timing meansfor controlling the period of operation of the heat-collecting shoe,said means for controlling the heat collecting shoe being responsive tothe timing means.

7. An. apparatus according to claim 6, and means operating said timingmeans so that whenever the braking means are actuated theheat-collecting shoe is maintained in operative position for apredetermined time interval after the braking means moves out ofoperative relation with the rotational component.

8. Apparatus according to claim 6, wherein the control means for thebraking means comprises a hydraulic circuit and the means controllingthe shoe is a hydraulic control connected to the said circuit via apressure restrictor, said timing means comprising a chamber of variablevolume connected as a shunt to the hydraulic control of theheat-collecting shoe, and a piston in said chamber which moves againstelastic means in cooperation with a leakage passage.

9. Apparatus according to claim 6, wherein the control means for thebraking means comprises a hydraulic circuit and the means controllingthe shoe is a hydraulic control connected to said circuit via a pressurerestrictor, the timing means comprising an electromagnet with a plungercore, the plunger core being coupled to a valve of the pressurerestrictor and said electromagnet having a feed controlled by a bellowsof calibrated leakage associated with said plunger core.

1. An apparatus comprising a rotational component, braking means for applying braking torque to the rotational component, control means for the braking means, a heat-collecting shoe for absorbing heat from the rotational component and having a coefficient of friction less than 0.3, a heat conductivity greater than 0.2 cal./cm.sec.* C. and being spaced from the braking means peripherally of the rotational component, the heat-collecting shoe developing a frictional couple with the rotational component which is at most 50 percent of the tangential braking force developed by the braking means with the rotational component, means normally holding the heat-collecting shoe out of contact with the rotational component, and means controlling the shoe for urging it towards the rotational component, said means controlling the shoe being operatively coupled to said control means for the braking means such that when said control means for the braking means is actuated to apply the braking means, the heat-collecting shoe is moved into hEat-absorbing contact with the rotational component.
 2. An apparatus according to claim 1, wherein said heat-collecting shoe has an internal cooling circuit, and means for circulating a cooling fluid through said cooling circuit.
 3. Apparatus according to claim 1, wherein the control means for the braking means comprises a hydraulic circuit and the means controlling the shoe is a hydraulic control connected to the said circuit via a pressure restrictor.
 4. Apparatus according to claim 1 wherein the heat-collecting shoe is arranged adjacent the braking means, in the direction of rotation of the rotational component.
 5. Apparatus according to claim 1, wherein the rotational component is a brake disc.
 6. An apparatus according to claim 1, further comprising timing means for controlling the period of operation of the heat-collecting shoe, said means for controlling the heat-collecting shoe being responsive to the timing means.
 7. An apparatus according to claim 6, and means operating said timing means so that whenever the braking means are actuated the heat-collecting shoe is maintained in operative position for a predetermined time interval after the braking means moves out of operative relation with the rotational component.
 8. Apparatus according to claim 6, wherein the control means for the braking means comprises a hydraulic circuit and the means controlling the shoe is a hydraulic control connected to the said circuit via a pressure restrictor, said timing means comprising a chamber of variable volume connected as a shunt to the hydraulic control of the heat-collecting shoe, and a piston in said chamber which moves against elastic means in cooperation with a leakage passage.
 9. Apparatus according to claim 6, wherein the control means for the braking means comprises a hydraulic circuit and the means controlling the shoe is a hydraulic control connected to said circuit via a pressure restrictor, the timing means comprising an electromagnet with a plunger core, the plunger core being coupled to a valve of the pressure restrictor and said electromagnet having a feed controlled by a bellows of calibrated leakage associated with said plunger core. 